Journal of Atrial Fibrillation – Journal of Atrial Fibrillation & Electrophysiology (JAFIB-EP)

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These are curated opinions and are not peer-reviewed.


Kimberly D. O’Donogue

Content Contributor

Questions : What type of pacing is being performed in the following electrogram? What is your interpretation?


Accessory Pathway ERP

Each impulse in the drive train (S1) captured the atrium and conducted to the ventricle. However, notice the wide QRS complex due to the delta wave which demonstrates activation down an accessory pathway. On S2, the impulse still conducted to the ventricle but through the AV node. The A to V interval is longer and there is no delta wave. The effective refractory period of the accessory pathway has been reached and it is no longer able to conduct.